Chem Help Essay

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Practice Test for 6.1-6.3 1. Complete the following molarity calculations: a. What is the molarity of a solution containing 25.3 grams of copper (II) chloride dissolved in 140 mL of water? b. How many grams of sodium hydroxide are needed to make 2 L of a 0.05 M solution? 2. A student dissolves 0.350 moles of potassium nitride (K3N) in 0.650 L of water. c. Calculate the molarity of the solution. d. What is the concentration of potassium ions? e. What is the concentration of nitride ions? f. What is the total concentration of ions? 3. How many times more acidic is a solution with a pH of 3 than a solution with a pH of 5? 4. Complete the following calculations and indicate whether the substance is acidic, basic, or neutral: g. What is the pH of a solution with a pOH of 11.4? h. What is the hydrogen concentration of a solution with a hydroxide concentration of 6 x 10-5? i. What is the hydrogen concentration of a solution with a pOH of 3.7? j. What is the pH of a substance with a hydroxide concentration of 4 x 10-5? k. What is the hydroxide concentration of a substance with a pOH of 8.5? 5. Write the dissociation equation for each of the following: l. sodium sulfate m. magnesium hydroxide n. calcium bromide. 6. Draw the Lewis structure for CH3Cl. o. How many valence electrons does this molecule have? p. What is the shape of this molecule? q. What is the bond angle? r. Is the molecule polar or nonpolar? s. What is the dominant intermolecular force present in this molecule? Answers: 1a. 1.34 M; b. 4 grams; 2a. 0.538 M; b. 1.614 M; c. 0.538 M; d. 2.152 M; 3. 100 times; 4a. 2.6, acidic; b. 2 x 10-10 M, basic; c. 5.01 x 10-11 M, basic; d. 9.61, basic; e. 3.2 x 10-9 M, acidic; 5a. Na2SO4 → 2 Na+ + SO42-; b.

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